One of the problem for low budget band online streaming is the mixing part. The biggest challenge is getting the mix right. Why is it hard? Guitar and other instruments have their own amplifier so when you are doing the mix, you would likely decrease the level of these instruments to the main mix. If you are feeding the main mix into your online live feed, chances are these instruments are too silent on the main mix.
This circuit can be use as a headphone amp mixer with built in DI box so you can directly feed the output into the mixer. There are 2 volume knobs, one knob is used for your instrument volume and the other knob can be used as a monitor level feed from the mixer.
The circuit is simple opamp circuits. A balanced output driver for D.I. box output, a headphone amplifier for driving headphone, a differential amplifier for balanced input and a non-inverting amplifier for a direct guitar input.